Devices for drawing in a web of material

ABSTRACT

A device for drawing a web of material into a machine, such as a printing press includes a draw-in mechanism that can be advanced along a draw-in path, and to which the web of material can be coupled. The draw-in mechanism can be driven by an electric motor that can be regulated or controlled in response to measurement data which is determined during the draw-in process. The motor can be regulated or controlled in synchronism with another unit of the machine, which other unit is mechanically driven independently of the electric motor.

FIELD OF THE INVENTION

The present invention is directed to devices for drawing a web ofmaterial into a processing machine. The device includes a web draw-inmechanism which is driven, independently of the processing machine, byan electric motor.

BACKGROUND OF THE INVENTION

Web drawing devices are employed in printing presses for conveying thestart of a web of material along a desired draw-in path through theprinting press. This is required, for example, for a draw-in inconnection with a new production. This is also always required in thecase where a web of material was torn during the printing process,because then the start of the new web of material cannot be pulledthrough in the manner of a flying roll change. Furthermore, in modernprinting presses the printing groups can be reached by the web to beprinted along different conveying paths in order to be able to obtaincorrespondingly different printing results. In case of a change-over inthe conveying path, the fresh web of material must be drawn in along theappropriate draw-in path.

A device for drawing a web of material into a processing station isknown from DE 94 15 859 U1. The draw-in mechanism, which is in the shapeof a tape, can be rewound from a winding roll at the inlet of theprocessing station to a winding roll at the outlet of the processingstation.

A device for drawing webs of material into rotary printing presses isknown from DE 22 41 127 A1. The draw-in mechanism, which is embodied inthe form of a spring steel strip, can be pushed from the outlet of theprinting press along different draw-in paths, between which switchingcan be performed by the use of shunts. In this case, the draw-inmechanism is driven by a stationarily arranged drive wheel, which drivewheel comes into positive contact with the draw-in mechanism and pushesthe draw-in mechanism along its entire length through the printingpress.

EP 0 418 903 A2 discloses a device for drawing in a web of material. Adraw-in mechanism is driven by a motor which is controlled as a functionof measured data obtained in the draw-in process. Control is performedwith a view to a constant draw-in speed, or to a constant number ofrevolutions.

A device for drawing in a web of material is disclosed in DE 94 09 390U1. A draw-in mechanism is driven by a step motor. A conveying distancealready traveled by the draw-in mechanism is detected by sensors.

SUMMARY OF THE INVENTION

The object of the present invention is directed to providing devices fordrawing in a web of material.

In accordance with the present invention, this object is attained by theprovision of a draw-in mechanism that is usable to draw a web along adraw-in path in a web processing machine. The web draw-in mechanism isdriven by an electric motor which is driven independently of at leastone other unit of the web processing machine. The electric motor and adrive mechanism for the at least one other unit are regulated, orcontrolled in relation to each other. The electric motor driving thedraw-in mechanism can be regulated with respect to a pre-set moment atthe electric motor. The electric motor can also be regulated as afunction of a conveying speed of the draw-in mechanism.

A particular advantage of the present invention lies in that theflexibly and finitely embodied draw-in mechanism can be wound onto areel body, so that only very little space is required for storing theportion of the draw-in mechanism which is not pushed into the printingpress.

The embodiment of the draw-in mechanism as a finite draw-in mechanism,which can be fastened with one end on a reel body and which can becompletely wound on the reel body, has a great advantage. In contrast toendless or re-windable draw-in mechanisms, it is possible, in accordancewith the present invention, to realize different draw-in paths viashunts.

Basically, the driving of the draw-in mechanism can be assured in anyarbitrary manner. In accordance with a preferred embodiment of thepresent invention, the draw-in mechanism is driven by the driven reelbody, which can be driven in two directions of rotation for winding, orfor unwinding, the draw-in mechanism. Thus, a separate drive wheel fordriving the draw-in mechanism can be omitted.

Preferably, a controllable electric motor is employed for driving thereel body. The reel body can thus be driven in a controlled manner atdifferent rotational speeds and/or torques. A constant conveying speed,or a comparable moment, can be set at the draw-in mechanism by anappropriate measurement, for example of the feeding speed of the draw-inmechanism, or of the applied moment. However, in a different embodiment,the electric motor can also be correspondingly controlled with respectto a speed, for example frequency or a torque output.

A multitude of sensors are usable for measuring the conveying speed ofthe draw-in mechanism. A particularly simple construction results if theeffective circumference of the reel body, by use of which the draw-inmechanism is unwound, and the rotational speed of the reel body aremeasured, or are preset in the form of a graph. The effectivecircumference of the reel body is understood to be the value resultingfrom the circumference of the reel body itself and the circumference ofthe layers of the draw-in mechanism which are still wound on the reelbody. By evaluating these two measured values, it is possible, in asimple manner, to determine the linearly directed feeding speed of thedraw-in mechanism and thereafter to set that feeding speed to a commandvalue by an appropriate regulation of the rotational speed of the reelbody. Also, a corresponding dependence of the command value rpm from thenumber of revolutions performed, stored in the form of a control curvein the software, is conceivable.

It is necessary, in the course of pushing the draw-in mechanism throughthe printing press, to transmit considerable compressive forces in orderto overcome the frictional forces existing in the guide devices.Therefore, the draw-in mechanism can be preferably embodied in the formof a steel tape, and in particular in the form of a spring steel tape,since steel tapes have great flexibility and at the same time cantransmit large tensile or compressive strains. However, the use of alsoknown plastic tapes, chains or correspondingly embodied cables is, ofcourse, also possible.

In order to reduce, as much as possible, the frictional forces occurringat the draw-in mechanism, which frictional forces must be overcome bythe drive mechanism, the draw-in mechanism can be sheathed, at least inpart, in a friction-reducing layer. For example, it is possible tosheathe the draw-in mechanism, which is in the form of a steel tape, ina layer of plastic in order to combine, in this way, the materialproperties of the steel tape of high tensile or compressive resistancewith the desired low-friction material properties of the plastic.

BRIEF DESCRIPTION OF THE DRAWING

A preferred embodiment of the devices for drawing in a web of material,in accordance with the present invention is represented in the soledrawing FIGURE and will be described in greater detail in what follows.The sole drawing FIGURE shows a printing press with a device fordrawing-in a web of material in a schematically represented sideelevation view.

DESCRIPTION OF THE PREFERRED EMBODIMENT

A draw-in device 08, 09, 11, for use in the drawing in a start of a webof material is provided in a processing machine 01. The processingmachine 01 may be, for example a printing press 01, for use inprocessing webs of material, for example paper webs.

The printing press 01, which is schematically represented in sideelevation in the sole drawing, has two printing units 02, 03, each withtwo double printing groups, or four printing groups. The printing press01 also has three roll changers 04, 06, 07.

The three devices 08, 09, 11 for drawing a web of material into theprinting press 01 are arranged downstream of the outlet of the printingunits 02, 03. Each of the web draw-in devices 08, 09, 11 consists of adraw-in mechanism 12 embodied in the form of a spring steel tape 22,which can be wound on a reel body 13, which is embodied in arotationally symmetrical manner.

In a first preferred embodiment, the reel body 13 is driven by the useof a motor 17, for example an electric motor 17, which motor 17 is onlyrepresented in connection with the upper reel body 13, and in particularreel body 13 is driven by the use of a controllable a.c. motor 17 with afrequency converter. Control is performed in such a way that, with achanging effective reel radius, the number of revolutions of the reel ischanged in such a way that an almost chronologically constant draw-inspeed of the draw-in mechanisms 12, such as the spring steel tape 22 isprovided.

In another mode of operation, regulation of the electric motor 17 canalso take place in such a way that the electric motor 17 is operated atany time with a defined presettable moment and, in this way, results ina largely constant web draw-in force. This moment can be constant, forexample for short draw-in distances, and for longer draw-in paths it cantake place, for example, along a predeterminable curve.

In a general way, the electric motor 17 can be controlled as a functionof measured data obtained in the course of the draw-in, which measureddata provide information regarding the progress and/or existing moments.

In a second preferred embodiment, which is represented by dashed linesin the sole drawing, the draw-in mechanism 12 can be driven by the useof a synchronous drive mechanism 14 that is constituted by two rollersenclosing the draw-in mechanism 12. The synchronous drive mechanism 14can also have a driven roller and an undriven roller, which drivenroller can be placed against the undriven roller. The reel body also hasa motor which, in this second embodiment, need not be controllable inthe way of the electric motor 17 discussed in connection with the firstembodiment.

In this second preferred embodiment, the electric motor 17, which isshown in dashed lines is arranged driving the synchronous drivemechanism 14, also shown in dashed lines, and is controlled, in the samefashion as discussed above, to provide a constant draw-in speed or aconstant, or presettable moment.

In both examples, the reel body 13 has a center shaft on which the oneend of the draw-in mechanism 12 is fixed. Moreover, lateral flanges orcheeks are provided at the ends of the center shaft against which theportion of the draw-in means 12 wound on the reel body 13 is laterallysupported.

It is also possible, in accordance with the present invention, toarrange only a single draw-in device 08, 09, 11 downstream of the outletof the printing units 02, 03. A selection of the draw-in path can berealized by the arrangement of shunts 16, which are not represented indetail in the sole drawing FIGURE.

By driving the reel body 13 in a clockwise direction, as seen in thesole drawing, the finite draw-in mechanism 12 can be wound off the reelbody 13 and pushed, depending on the position of the shunts 16, whichare only schematically represented, along selected ones of differentdraw-in paths that extend through the printing press 01. In the process,the draw-in mechanism 12 is guided by guide rails, which are notspecifically represented. In the area of the inlet to the printing press01, the draw-in mechanism 12 can be connected with the start of therespective paper web at one of the roll changers 04, 06 or 07, so thatthe paper web is conveyed through the printing press 01 by retractingthe draw-in mechanism 12 along a desired draw-in path.

The control of the electric motor 17 driving the reel body 13 inaccordance with the first preferred embodiment, can also be applied inconnection with draw-in devices wherein a finite length draw-inmechanism 12 is rewound from a reel body, not represented, in the areaof the roll changers 04, 06, 07 to a reel body 13 located downstream ofthe outlet of the printing units 02, 03, and vice versa.

In an advantageous embodiment of the present invention, the individualcomponents of the printing units 02, 03, for example the cylinders ofthe printing groups individually or in pairs, the entire printing groupof the printing unit, the driven rollers of the paper guide device, thefolding apparatus, and possibly additional rotatable elements of theprinting press, each can have their own drive motor. Matching, orsynchronization of these units, takes place by use of a so-called“virtual guide axis” or “electronic shaft”, which electrically connectsthe regulating or control devices of the units with each other. Aregulating device, or a control device of the electric motor for thesynchronous drive mechanism 14 or for the direct drive of the reel body13 is electrically connected with this “virtual guide axis”. A speed ofthe draw-in mechanism 12 approximately corresponds to the respectivesurface speed of the units in contact with the web, for example therespective cylinders of the printing units 02, 03, the driven paperguide or draw-in rollers, not represented, the roll changers 04, 06, 07,and the like.

The respective number of revolutions, or the angular speed of theelectric motor 17 for the synchronous drive mechanism 14, or for thereel body 13, is determined in an electronic circuit or in a computerunit, possibly by using a controllable frequency converter, which ispresent at the electric motor 17. In a reverse manner, it is alsopossible to preset a possibly constant draw-in speed, wherein theremaining units relating to the draw-in process are driven with acorresponding circumferential speed via the electronic shaft. In thecase of the direct drive of the reel body 13, the change of theeffective diameter must be superimposed on the desired or requireddraw-in speed in the described way.

The preferred embodiment for regulating the electric motor 17, inrespect to a moment, is directed to a limitation of the stress on theweb, or on the connection between the web and the draw-in mechanism 12during the draw-in process. In the case of a directly driven reel body13, this regulation is performed, as already partially explained above,by taking into consideration the changing diameter of the web draw-inmechanism 12 situated on reel body 13. This consideration is taken, forexample, in an electronic circuit or in a computer unit by the use ofstored functions, for example, as a function of the revolutionsperformed, or of angles, or by means of the above mentioned measuredvalues. In addition, it is possible, by use of information regarding thealready taken and/or the remaining draw-in path determined bymeasurements or in another way, for example by the revolutions made, orthe angles to provide a superimposition of a moment required forovercoming the friction.

The angular speed, or the number of revolutions, can be detected at thereel body or at the electric motor 17, for example by the use ofincremental encoders and, as in the previously mentioned example, thisangular speed can be preset following an appropriate re-calculation viathe electronic shaft to the control or regulating devices of other,individually driven units. However, the determination of the draw-inspeed can also be performed in other ways on the draw-in path.

While preferred embodiments of a device for drawing in a web of materialin accordance with the present invention have been set forth fully andcompletely hereinabove, it will be apparent to one of skill in the artthat various changes in the number and configuration of the printingunits, the number and configuration of the roll changers, and the likecould be made without departing from the true spirit and scope of thepresent invention which is accordingly to be limited only by thefollowing claims.

1. A device for drawing a web of material into a processing machinecomprising: a flexible draw-in mechanism including a tape having afinite length, said tape having a tape first end and a tape second end,said draw-in mechanism being adapted to be driven for movement of saidtape second end along a draw-in path; a reel body, said tape first endbeing connected to said reel body, said tape having said finite lengthbeing windable completely on said reel body; an effective reel bodyradius, said effective reel body radius being changeable as a functionof an amount of said tape finite length wound on said reel body; and acontrollable electric motor usable to drive said reel body independentlyof the processing machine to cause said finite length tape to travelalong said draw-in path, said electric motor being controllable tomaintain a constant preset moment applied to said tape by saidchangeable effective reel body radius of said reel body driven by saidelectric motor to apply a constant draw-in force to said draw-inmechanism.
 2. The device of claim 1 further including at least one unitin the processing machine and wherein said electric motor usable todrive said reel body is mechanically independent of said at least oneunit in the processing machine.
 3. The device of claim 2 furtherincluding a drive mechanism for said at least one mechanicallyindependent unit and wherein said electric motor and said drivemechanism are regulated in relation to each other.
 4. The device ofclaim 1 wherein said electric motor is regulated as a function ofmeasurement data determined in a draw-in process.
 5. The device of claim1 further wherein said tape second end is connectable to a web ofmaterial.
 6. The device of claim 1 wherein said electric motor is ana.c. motor which is regulated by frequency conversion.
 7. The device ofclaim 1 wherein said flexible draw-in mechanism is a steel tape.
 8. Adevice for drawing a web of material into a processing machinecomprising: a flexible draw-in mechanism including a tape having afinite length, said tape having a tape first end and a tape second end,said draw-in mechanism being adapted to be driven for movement of saidtape second end along a draw-in path; a reel body, said tape first endbeing connected to said reel body, said tape having said finite lengthbeing windable completely on said reel body; an effective reel bodyradius, said effective reel body radius being changeable as a functionof an amount of said tape finite length wound on said reel body; and acontrollable electric motor usable to drive said reel body independentlyof the processing machine to cause said finite length tape to travelalong said draw-in path, said electric motor being controllable tomaintain a preset torque applied to said tape.